A cerebral aneurysm (i.e., an acute subarachnoid hemorrhage) is a cerebrovascular swelling on the wall of an artery that develops because of a congenitally weak cerebral artery or due to arteriosclerosis, a bacterial infection, a head wound, brain syphilis, etc. The cerebral aneurysm may develop suddenly without initial symptoms, and can cause extreme pain. In general, in 15% of cerebral aneurysm cases, the patient dies suddenly upon development of the cerebral aneurysm. In another 15% of cerebral aneurysm cases, the patient dies under medical treatment; and in 30% of cerebral aneurysm cases, the patient survives after treatment but feels an acute aftereffect. As such, a cerebral aneurysm is a very concerning development.
A cerebral aneurysm may be treated through either an invasive therapy or a non-invasive therapy. Of these, the non-invasive therapy typically fills the cerebral aneurysm with a micro-coil. Generally, filling the cerebral aneurysm with the micro-coil causes blood to clot, prevents an additional inflow of blood, and decreases the risk of a ruptured aneurysm (i.e., an embolization). Advantageously, the non-invasive therapy can ease the aftereffects of brain surgery and can shorten hospitalization time.
The system used in the non-invasive therapy typically includes a micro-coil and a delivery pusher for carrying the micro-coil to the patient's cerebral aneurysm. When the micro-coil is properly placed in or near the cerebral aneurysm, an operator (e.g., a physician) separates the micro-coil from the delivery pusher. To initiate detachment of the coil, current micro-coil systems generally require a thermal/power supply (for thermal or electrolytic detachment), or a mechanical detachment handle that is attached to the proximal end of the delivery pusher after the coil is positioned in the aneurysm.
Certain mechanical detachment systems employ the use of a core wire to remove an element that provides an interference fit between a tip of the core wire and some component of the coil. Certain other mechanical detachment systems have used interlocking arms that disengage when advanced beyond the micro-catheter tip, or a ball-screw mechanism that unscrews the coil from a tip of the delivery pusher when the pusher is rotated, or even hydraulic systems that eject the coil from the delivery pusher tip when the inside diameter is pressurized with saline.
Having to attach, however, a mechanical detachment handle (or some other element, such as a power supply box) to the proximal end of the delivery pusher after the coil is positioned in the aneurysm in order to initiate detachment of the coil is problematic. For example, the delivery pusher and thus the coil may inadvertently move while the detachment handle (or other element) is being attached. This may cause the coil to lose its proper placement within or near the cerebral aneurysm. In addition, attaching the detachment handle (or other element) lengthens the operating time. Where a procedure requires many such coils to be delivered, this can add significantly to the overall operating time.
In addition still, currently available implantable devices, such as embolic micro-coils, often employ a polymeric stretch resistant member to maintain the shape of the micro-coil and to prevent it from unfurling during delivery to a patient's body. During manufacture, in order to form a mechanical securement (e.g., a junction) between the stretch resistant member and the micro-coil, the stretch resistant member is generally melted at, and coupled to, one or both end(s) of the micro-coil. The process of melting the polymer can, however, significantly reduce the strength of the stretch resistant member at the junction. As such, when the micro-coil is placed under tension, the melted junction typically, and disadvantageously, fails at a force below the inherent tensile strength of the polymeric stretch resistant member.
Accordingly, needs exist for improved implantable assemblies and for methods of manufacturing and using the same, as well as for improved systems and methods for delivering the implants to a vascular disorder, such as a cerebral aneurysm.